1. Field of the Invention
The present invention relates to a capacitive type touch sensor in which a film sensor member is adhered to a rear surface of a cover glass which is attached to an LCD part of the electronic apparatus, particularly to one having optical functionality such as circularly polarized light and giving the phase difference.
2. Background Information
Conventionally, the capacitive type touch sensor, in which a film sensor member is attached to a rear surface of a cover glass of the display window of the electric device, is arranged on an upper surface of display such as LCD (Liquid Crystal monitor) and OLED (Organic Light Emitting Diode). In this arrangement, since daylight is reflected at an interface between the air layer and the film sensor member, as well as an interface between the air layer and the display, the contrast on the display is lowered, which is a problem.
It is possible to restrain the reflection to 50% by adding a polarization plate between the cover glass and the film sensor member. In this case, even when the touch sensor, to which the polarization plate is added, is arranged on the LCD, if the absorption axis of the polarization plate is matched with that of the LCD, it is possible to prevent the brightness of the LCD from being lowered.
In addition, if the touch sensor is designed such that a polarization plate and a λ/4 phase difference film are added between the cover glass and the film sensor member in this order from the cover glass side, i.e., a circularly polarized light filter is added, it is possible to further restrain the reflection compared to a case of adding only the polarization plate.
However, in the capacitive touch sensor with circularly polarized light function in which the circularly polarized light filter consisting of the polarization plate and the λ/4 phase difference film is added, thickness of the circularly polarized light filter is added, causing the thickness of a product into which the touch sensor is assembled increases, which is a new problem. Therefore, one type of capacitive type touch sensor is proposed as shown in paragraph 0071 of Patent Citation 1, recently. The capacitive type touch sensor includes a film sensor member of a structure employing a two layer system, a polarization plate, and a cover glass. The film sensor member includes a first conductive film and a second conductive film. The first conductive film has an upper surface on which a first conductive layer such as ITO is provided. The second conductive film is adhered onto the first conductive layer and has an upper surface on which a second conductive layer such as ITO is provided. The polarization plate and the cover glass are adhered to the upper surface of the film sensor member. A λ/4 phase difference film is employed as a base member of the second conductive film. According to the touch sensor described in Japanese Patent Publication 2011-81810, since the λ/4 phase difference film is employed as a base member for the conductive layer of the film sensor member, and not as a separate member provided on the film sensor member, it is possible to provide a thin capacitive touch sensor with circularly polarized light function.
In addition, conventionally, when observing the LCD through the polarized sunglass, coloring and decrease in transmission factor occur depending on the polarization plate angle on the LCD side. In order to overcome the problem, it has been proposed for a long time and is described in Japanese Patent Publication H03-174512 that a λ/4 phase difference film is arranged between the polarized sunglass and the LCD, for example.
In the capacitive type touch sensor market, it has been required to further narrow the frame (i.e., maximizing the size of the central window on which images are displayed, and minimizing the size of the outer frames surrounding the window portion), in addition to the above-described reduction in thickness. However, generally, in the film sensor member of the touch sensor, since the routed wiring circuit formed on the peripheral frames are manufactured using a screen printing with silver paste, there are limitations for further pursuing the frame narrowing.
Accordingly, it is an object of the present invention to solve the above-described problem, i.e., to provide a capacitive type touch sensor with optical functionality, in which the intended optical functionality is performed, a thin thickness is achieved of the product to which the touch sensor is assembled, and frame narrowing is achieved.
According to a first aspect of the present invention, a capacitive type touch sensor with circularly polarized light function includes a cover glass, and a capacitive type film sensor member adhered to a rear surface of the cover glass.
The film sensor member includes:
a transparent base sheet including a λ/4 phase difference film;
a transparent conductive film formed so as to have an electrode pattern formed on a central window and a fine wiring routed circuit pattern formed on an peripheral frame, both of the patterns being formed on both sides of the base sheet; and
a light-blocking conductive film laminated on each of the fine line routed circuit patterns of the transparent conductive film.
According to a second aspect of the present invention, a capacitive type touch sensor with optical functionality according to the first aspect is provided, which further includes a polarization plate between the cover glass and the film sensor member.
According to a third aspect of the present invention, a capacitive type touch sensor with optical functionality according to the first aspect or the second aspect is provided, in which the bases sheet of the film sensor member is a single layer of the λ/4 phase difference film.
According to a fourth aspect of the present invention, a capacitive type touch sensor with optical functionality according to the first aspect or the second aspect is provided, in which the base sheet of the film sensor member is a laminated body made of the λ/4 phase difference film and an optical isotropy film adhered to each other.
According to a fifth aspect of the present invention, a capacitive type touch sensor with optical functionality according to the second aspect is provided, which further includes a λ/2 phase difference film between the film sensor member and the polarization plate.
According to a sixth aspect of the present invention, a capacitive type touch sensor with optical functionality according to the second aspect is provided, in which the base sheet of the film sensor member is a laminated body made of the λ/2 phase difference film and a λ/4 phase difference film adhered to each other, and the λ/2 phase difference film of the laminated body is arranged towards the side of the polarization plate.
According to a seventh aspect of the present invention, a capacitive type touch sensor with optical functionality according to any of the first through sixth aspect is provided, in which the film sensor member includes a frame-like light-blocking layer. The frame-like light-blocking layer is formed on a periphery of the front surface of the light-blocking conductive film, on which the transparent conductive film have been formed. The frame-like light-blocking layer is made of a product based on a color resist material that has been exposed and developed.
According to the capacitive type touch sensor with optical functionality of the present invention, since the film sensor member includes the transparent base sheet having the λ/4 phase difference film, it overcomes the problem of coloring and a decrease in transmission factor due to polarization plate angle on the LCD side, when observed through the polarized sunglass. It also prevents the interference pattern (fringe) when viewed obliquely.
According to the capacitive type touch sensor with optical functionality of the present invention, the polarization plate is provided between the cover glass and the film sensor member, the film sensor member includes the transparent base sheet having the λ/4 phase difference film, and the polarization plate and the λ/4 phase difference film constituting a circularly polarized light filter. As a result, it is possible to cut off the ambient light reflected at the interface between the air layer and the film sensor member and the interface between the air layer and the display, thereby overcoming a problem of decreased contrast on the display.
In addition, since the λ/4 phase difference film is used as a base material for the conductive layer of the film sensor, and not formed as a separate member on the film sensor member, the thickness can be reduced.
In addition, since the film sensor member includes a transparent base sheet having the λ/4 phase difference film, a transparent conductive film formed on both sides of the base sheet so as to form an electrode pattern on the central window and a fine line wiring for routing on the peripheral frame, and a light-blocking layer laminated on the fine line routed circuit of the transparent conductive film, it is possible to obtain a capacitive type touch sensor with optical functionality that achieves frame narrowing in which line width and pitch of the fine line wiring for routing are narrow.